"The airplanes here are an easy target because they fly at very low altitude and this is the best position for this weapon to be used."

Its discovery poses a headache for Western countries such as Britain which closely monitors airport security across Egypt and is weighing up whether to resume tourist flights to Sharm el-Sheikh after a Russian jet was blown up by terrorists linked to Islamic State in 2015.

Yousry's post from Saturday quickly went viral in Egypt but he took it down fearing it would land him in trouble with the country's authoritarian government.

Instead he replaced it with the cryptic sentence: "Fishing in troubled waters is not my style."

Arms expert James Bevan examined photos of the launcher at the request of The Telegraph.

Bevan, executive director of Conflict Armament Research, said it was impossible to tell if the weapon was real based on a social media photograph but that it looked like an SA-7b, a common portable anti-aircraft launcher.